Camshaft adjusters are used in internal combustion engines to vary the control times of the combustion chamber valves. Adjusting the control times to the instantaneous load and rotational speed reduces consumption and emissions. The vane-type adjuster is a common design. Vane-type adjusters have a stator, a rotor and a drive wheel. The rotor is usually rotatably fixedly connected to the camshaft. The stator and the drive wheel are also connected to each other, the rotor being located coaxially to the stator and within the stator. The rotor and stator form oil chambers (vanes), to which oil pressure may be applied and which permit a relative movement between the stator and rotor. The vane-type adjusters furthermore have various sealing covers. The assembly having the stator, drive wheel and sealing cover is formed by multiple screw connections.
A camshaft adjuster is known from U.S. Pat. No. 6,666,181 B2. Rotor 30, which is the output element, has a bypass in addition to the known hydraulic medium ducts. The bypass transports the displaced hydraulic medium from one working chamber to the oppositely acting working chamber. Once the bypass is covered by the stator, the driving element, this hydraulic medium flow stops. The rotor is now located in a central position. The bypass is controlled by a control piston which is able to permit or block the hydraulic flow from a bypass to a hydraulic medium duct. In known methods, the conventional hydraulic medium ducts are provided with check valves to use the camshaft alternating torques for adjustment by redirecting the hydraulic medium volume to be displaced from one working chamber to the oppositely acting working chamber at the point in time of a camshaft alternating torque. In the corresponding axial position of the control piston, the hydraulic medium ducts which repump the hydraulic medium flow in the desired adjusting direction of the rotor are switched to the hydraulic medium flow.